10.2 Flashcards
What is the goal antimicrobial drug
Disrupt cell processes or structures of bacteria, fungi, or protozoa
Inhibit virus replication
Interfere with the function of enzymes required to synthesize or assemble macromolecules
Destroy structures already formed in the cell
Selectively toxic definition
kill or inhibit the actions or synthesis of molecules in microorganisms but not vertebrate cells
What features make a drug an excellent selectively toxic drug
Drugs with excellent selective toxicity block the synthesis of the bacterial cell wall (penicillins).
Human cells lack the chemical peptidoglycan and are unaffected by the drug.
Drugs most toxic to humans are
Drugs that act upon a structure common to both the infective agent and the host cell (cell membrane)
As characteristics of the infectious agent are more and more similar to the host cell, selective toxicity becomes more difficult to achieve
Goals of chemotherapy
identifying structural and metabolic needs of a living cell and removing, disrupting, or interfering with these requirements
What are the antimicrobial drug categories?
Inhibition of cell wall synthesis
Inhibition of nucleic acid structure and function
Inhibition of protein synthesis
Interference with cell membrane structure and function
Inhibition of folic acid synthesis
effective against more than one group of bacteria:
Tetracycline antibiotics
Broad-spectrum drugs
: target a specific group:
Polymyxin
Narrow-spectrum drugs
Describe the penicillins
Original penicillin was narrow-spectrum and susceptible to microbial counterattacks.
Molecule has been altered and improved upon over the years
Later penicillins overcome the limitations of the original molecule.
How do bacteria with biofilms behave
Bacteria in biofilms behave differently than when they are free-living:
Often unaffected by antimicrobials
Antibiotics often cannot penetrate the sticky extracellular material surrounding biofilms.
Bacteria in biofilms express a different phenotype and have different antibiotic susceptibility profiles than free-living bacteria.
How do you treat bacteria with biofilms
Biofilm treatment strategies:
Interrupting quorum sensing pathways
Daptomycin: shown success
Adding DNAse to antibiotics aids penetration through extracellular debris
Impregnating devices with antibiotics prior to implantation
Some antibiotics cause biofilms to form at a higher rate than they normally would.
Unique challenges in the chemotherapeutic treatment of viruses
Infectious agent relies on a host cell for the vast majority of its metabolic functions.
Disrupting viral metabolism requires disruption of cellular metabolism.
Measles, mumps, and hepatitis are prevented through the use of vaccines.
AIDS, influenza, and the common cold attest to the need for more effective medications for the treatment of viral infection.
Major modes of action of antiviral agents:
Barring penetration of the virus into the host cell
Blocking transcription and translation of viral molecules
Preventing maturation of viral particles
DRACO: “double-stranded RNA-activated caspase oligomerizer”
Breakthrough antiviral treatment currently being tested
